www.flightcrewfinder.com is built in Drupal 6 with contrib modules and it brings together elements of social networking with relevant news items, recommendation, resources and jobs to provide everything that someone in the aviation industry needs to find a job.
We have linked in with other social networking sites and all our forum, blog, news, articles, jobs etc get posted directly to twitter while we keep our fans updated on Facebook and LinkedIn. I have been really impressed with how well the twitter module works. I have set it up so that forum posts, blog, news and articles automatically get posted to twitter. I have then set up a rule for new companies and jobs where it will post to twitter once certain conditions have been met. Users are able to use the #tag input format and the integration is so seamless you don't even realise its going on.
For Facebook and LinkedIn it is more of a manual process but they both drive a lot of traffic our way. Facebook especially brings a lot of people and I my next item on the agenda is to begin using the Gigya Socialize Module.